1. Field of the Invention
The present invention relates to door locks, particularly mortise locks, in which a trim mechanism mounted on the surface of the door has a handle turning a spindle that extends into the door to operate a lock mechanism mounted therein. More specifically, the present invention relates to the spindle that extends between the trim mechanism and the lock mechanism when the distance between those two mechanisms varies due to varying door thicknesses.
2. Description of Related Art
Mortise locks typically have a pair of trim mechanisms mounted on opposite faces of a door to operate the lock mechanism mortised into the door. The lock mechanism includes a latchbolt that engages the door frame to latch the door closed and the trim mechanisms include corresponding handles that allow the user to open the door by retracting the latchbolt when the door is unlocked.
In this type of design, the retraction of the latchbolt into the lock mechanism is achieved by operating a handle which turns a spindle extending from the trim mechanism to the lock mechanism. Different types of handles may be incorporated into the trim mechanism, such as lever handles, conventional knob handles, and paddle handles, etc., depending upon the intended use of the door. Knob handles are commonly used in private buildings. Lever handles are often used in public buildings and paddle handles are often found in hospitals or other locations where it is desirable to operate the door without grasping the handle with the hand.
In lever handles and knob handles, the spindle is usually turned directly by the handle. Rotating the handle turns the spindle which operates the lock mechanism. In paddle handles, there is a linkage or cam mechanism that converts an inward motion of the handle to spindle rotation.
In mortise locks, the lock mechanism is mounted halfway between the two opposed faces of the door (at the midplane of the door), and the handle trim mechanisms are surface mounted on the opposed faces of the door. Because doors can have different thicknesses, the distance from the face of the door to the midplane of the door will vary. Accordingly, the length of the spindle also varies, as it must correspond to the thickness of the door. The correct length for the spindle is particularly important for mortise locks that are designed with a pair of independent coaxial spindle hubs. This design allows handles on opposite sides of the door to be locked and operated independently.
With a pair of independent spindle hubs, the hubs are symmetrically located within the lock mechanism on opposite sides of the midplane of the door and the spindle from each trim mechanism cannot extend past the door midplane. If a spindle is too short, it will not fully engage its corresponding spindle hub. Alternatively, if the spindle is too long, it will bind and may jam the locking mechanism or the trim mechanism. The spindle length must be correct for the door thickness.
The need to match the spindle length to the door thickness is inconvenient, as the installer of the door lock must know the thickness of the door. It is also inconvenient for the supplier who must supply multiple spindles to match different door thicknesses or require that the purchaser specify the door thickness when the lock is purchased. Errors in selecting and installing the correct spindle are common and result in locks that jam, bind or fail to operate correctly. A related problem is that removable or replaceable spindles may fall out during handling or become misplaced before or during installation.
The present invention relates to solving the above problems where the lock mechanism is mounted at the door midplane and has surface mounted trim mechanisms on opposite sides of the door. It is specifically directed to the case where the trim mechanisms have independent spindles and where the spindles cannot extend beyond some maximum depth, to prevent binding, but must extend to at least some minimum depth to properly engage the lock mechanism. The invention is particularly suitable for the case where the spindle must be relatively short or where the trim mechanism provides very limited space for the spindle and related linkages or cams.
One example of a trim mechanism that has limited space is paddle trim. Paddle trim is often used in hospitals, restaurants, washrooms and public buildings where it is desirable to be able to open the door simply by pressing inward on the handle without contacting it with the hand. Paddle trim handle mechanisms permit the door to be opened by contacting the paddle handle with the elbow, the hip, etc. and does not require the hands to be free, nor does it require a handle to be turned or gripped with any force.
Because the paddle handle moves inward to open the door, paddle trim mechanisms use a cam hub that converts the inward motion of the paddle handle to a rotational motion of the spindle. A consequence of this design is that it severely limits the maximum length of the spindle. In more conventional trim mechanisms that do not require this conversion from inward to rotational motion, the spindle may project axially into the rotating knob or lever handle. In the paddle handle design, this is not practical and this limitation on the space available for the spindle makes it difficult to construct any type of mechanism to vary the length of the spindle as needed to accommodate the varying door thicknesses.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a retracting spindle mechanism for operating a door lock which automatically extends and retracts to accommodate different door thicknesses.
It is another object of the present invention to provide a retracting spindle mechanism for operating a door lock which comprises a single assembly and does not have separate loose parts.
A further object of the invention is to provide a retracting spindle mechanism for operating a door lock which fits within a limited depth.
It is yet another object of the present invention to provide a retracting spindle mechanism for operating a door lock which is suitable for use with a paddle handle trim mechanism.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The above and other objects, which will be apparent to those skilled in art, are achieved in the present invention which is directed to a retracting spindle mechanism for operating a door lock and to a handle trim mechanism incorporating the retracting spindle mechanism.
The retracting spindle mechanism includes a spindle having one end adapted to operate the door lock and another end driven by a trim mechanism handle. A pin is mounted in the spindle and a hub has a slot and an axial opening formed therein. The cross sectional shape of the axial opening is such that the spindle is engaged by the axial opening to rotate with the hub. The axial opening is sufficiently deep to allow the spindle to slide axially therein. The pin is engaged by the slot in the hub to retain the spindle in the axial opening. A spring surrounds a first portion of the hub, and the spring exerts an outward force on the spindle through the pin.
The spring is preferably a conical spring with progressively smaller coils. Each coil has an inner diameter and an outer diameter, and the inner diameter of each coil is at least as large as the outer diameter of each smaller coil in the spring. This allows the spring to collapse until it is approximately flat, thereby using very little space.
When the invention is to be used in a paddle handle trim mechanism, the hub includes a cam formed thereon which may have a roller on it to reduce friction. The cam and roller allow the pivoting action of the paddle handle to be converted into rotation of the spindle. The conical spring is particularly suitable for this implementation of the invention as it allows the maximum length and retracting motion for the spindle within the extremely limited space available between the paddle handle in the trim mechanism and the lock mechanism.
In one aspect of the invention, the slot extends transversely through the axial opening in the hub forming a pair of opposed slot openings in the hub. The pin extends through the opposed slot openings and transversely outward from opposite sides of the hub. The conical spring has a large end and a small end with the small end of the conical spring contacting the pin on opposite sides of the hub.
The invention also includes the retracting spindle mechanism in combination with a handle trim mechanism. In this combination, the handle trim mechanism includes a mounting plate for mounting to the exterior of a door, and a handle mounted to the mounting plate for motion between an open position and a closed position. The hub of the retracting spindle mechanism is rotatably mounted to the mounting plate and the handle rotates the hub as the handle moves between the open position and the closed position. The spring is positioned between the mounting plate and the pin to urge the spindle outwards and into full engagement with the lock mechanism.